Mentation test method and mentation test apparatus

ABSTRACT

The object of the present invention is to provides a mentation test method that can test mentation of a human such as conjecture of brain&#39;s mentation age, discrimination of early stage of dementia and prediction of onset of dementia in addition to diagnosis of prediction probability of onset of dementia and screening of mental functions of senile dementia patients, decision of the effect of rehabilitation of the aftereffects of cerebrovascular disfunction, investigation of the therapeutic effects of medicines and side effects such as sleepiness, testing of degree of intoxication, testing of peripheral attention visual field, testing of cerebral dominant hemisphere, testing of various psychoneurosis such as schizophrenia and cerebrovascular disorder (syndrome and diagnosis, and decision of the effects of rehabilitation and treatment), and check of the degree of fatigue. Another object of the present invention is to provide a mentation test apparatus capable of executing the method as described above.  
     The method according to the present invention comprises the steps of randomly disposing and displaying a given number of targets in a prescribed order on a screen of a display device, measuring the search response time for a test object to point each target in a prescribed order, and calculating mentation of the test subject based on the measured values.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method for testing mentationof humans, and a mentation test apparatus. More specifically, thepresent invention relates to a highly reproducible and reliablementation test method that is able to sensitively test human mentationwithout being affected by intelligence, educational carrier and theeffects of repeated learning, and a mentation test apparatus.

[0003] 2. Description of the Background Art

[0004] A mentation test method called TMT (Trail-Making-Test) has beenused for finding diseases such as cerebrovascular disorder,schizophrenia and dementia. In this method, test subjects are given atask to sequentially line the figures of 1 to 25 randomly distributed ona sheet of A4 paper within a period as short as possible in a mannersimilar to one stroke drawing. While the time required for a testsubject to complete the task, or to gain a score, is recognized to beaffected by the intelligence quotient of the subject as well as by agingto some extent, there are different opinions on the effect of the schoolcarrier.

[0005] Since the task can be achieved within a short period of time bysimultaneously proceeding two sorts of tasks of search of a target andmemory of locations of letters and figures other than the target in theTMT method, higher concurrent processing ability between recognition andretention of information (memory), or higher processing ability of theworking memory, results in better results.

[0006] However, many other functions such as flexibility of mentation,attention span (fatigue), visual search ability and motor ability arerequired besides the working memory for achieving the task of the TMTmethod. Accordingly, lower performance of the aged person is conjecturedas a result of age-related changes of these factors above.

[0007] However, it is impossible in the currently available TMT methodto analyze what factors have affected to what extent on the decrease ofthe score, thereby making it impossible to assess the working memoryability of aged persons and dementia patients.

SUMMARY OF THE INVENTION

[0008] Accordingly, one object of the present invention for solving theproblems in the conventional art is to provide a mentation test methodcapable of testing human mentation such as conjecture of brain mentationage, discrimination of initial dementia and prediction of onset thereofas well as diagnosis of onset prediction probability and screening ofmentation of the senile dementia patients, decision of therehabilitation effect on the aftereffects of the cerebrovasculardysfunction, therapeutic effects of medicines and investigation of sideeffects such as sleepiness, testing of intoxication, testing ofperipheral attention visual field, testing of the cerebral dominanthemisphere, testing of various neuropathy and mental disorder such asschizophrenia and cerebrovascular disorder (symptoms and diagnosis, anddecision of the effect of rehabilitation and treatment), and check ofmental fatigue. Another object of the present invention is to provide amentation test apparatus capable of executing the method describedabove.

[0009] The mentation test method according to the present invention(referred as a method according to the present invention hereinafter)for attaining the foregoing objects uses a technical method comprisingdisplaying a given number of randomly disposed targets to be pointed ina prescribed order on a screen of a display device, measuring a searchresponse time required for a test subject to search each target bypointing the target in a prescribed order, and calculating the testsubject's mentation based on the measured values.

[0010] In a method according to the present invention, many normal testsubjects are given a visual search task for pointing the targetsdisplayed on the screen of the display device in a prescribed order tomeasure the search response time for each target. Consequently, thecorrelation between the age and score can be statistically determined,and brain's mentation age can be conjectured from the statisticallydetermined correlation and score of each test subject.

[0011] In a different method according to the present invention, a testsubject is given a task in which mnemonic ability of the test subject isreflected on reduction of the search response time, and a task in whichmnemonic ability of the test subject is hardly reflected on reduction ofthe search response time to measure the search response time for eachtarget. Consequently, more accurate correlation between the age andscore can be statistically determined, and the brain's mentation age canbe more accurately conjectured from the statistically determinedcorrelation and score of each test subject.

[0012] In a different method according to the present invention, thetest subject is given a task in which mnemonic ability of the testsubject is reflected on reduction of the search response time, and atask in which mnemonic ability of the test subject is hardly reflectedon reduction of the search response time to measure the search responsetime for each target. Consequently, processing ability of the workingmemory can be analyzed by calculating contraction rate of the searchresponse time arising from the working memory.

[0013] Prediction probability of early onset of dementia or onset ofdementia can be diagnosed by statistically determining the contractionrate of the search response time arising from the working memory of thenormal subjects and dementia patients, and by comparing thestatistically determined contraction rate of the search response timearising from the working memory with that of each test subject.

[0014] When the test subject is given a task in which mnemonic abilityof the test subject is hardly reflected on reduction of the searchresponse time in the method according to the present invention, and whenthe search response time is measured for each target, then the searchresponse time for the late turns of search tends to be prolonged,besides it is further elongated as the test subject is aged.

[0015] Delay of this search time is thought to arise from fatigues, andthe causes of the fatigues include intoxication, effects of medicines,side effects of medicines, asthenopia and mental fatigue.

[0016] Therefore, the correlation between the cause and achievement isstatistically determined using, for example, age as a parameter forevery causes or for every time when two or more of these causes competeto one another in the present invention. It is then made possible todiagnose the extents of intoxication, effects of medicines, side effectsof medicines, asthenopia and mental fatigue by comparing the correlationwith the score of each test subject.

[0017] The other causes of arising delay of the search response includeconstriction of peripheral attention visual field and loss of exercisefunction. The extents of constriction of peripheral attention visualfield and loss of exercise function can be also diagnosed by collectingstatistical data by the same method as described above, and by comparingthe statistical data with the test score of each test subject.

[0018] The method according to the present invention will be describedin more detail hereinafter.

[0019] While the display device comprising a screen for displayingtargets is not particularly restricted so long as the display device isable to switch the display image on the screen for every responses ofthe test subject, it is preferable that the display device can quicklyswitch the screen and is excellent in the degree of freedom for settingimage contents.

[0020] For example, a display device like a paper picture show may beemployed, whereby the device comprises a roll paper for sequentially andcontinuously printing the images that change for every response of thetest subject, and the roll paper is wound from one end to the other endfor every screen when the test subject show a correct response. However,it is preferable to use a display device that can display the targets onthe screen by electronic control that can rapidly switch the screen andis excellent in the degree of freedom in setting the contents of theimages, or a display device that can display the targets on the screenby computer control.

[0021] Although the number of the targets to be displayed is limited ona sheet of paper, the computer controlled display method is able to beinfinitely continued by erasing the pointed targets from the screen andcreating new targets. Since the response time is gradually delayed byproceeding the search responses for pushing the points, analysis ofreadily occurring fatigue is possible from the degree of delay of theresponse time. It has been already shown that response delay phenomenonis observed at an earlier time in the patients with chronic fatiguesyndrome than in normal subjects, which enables the patients withchronic fatigue syndrome to be discriminated.

[0022] The representative display device of this sort includes a cathoderay tube (CRT) display device, a liquid crystal display device and adichromic mirror display device.

[0023] Usually, a display device available has target pointing meanscomprising a cursor displayed on the screen, a cursor control means forcontrolling the display position of the cursor in accordance withoperations by the test subject, and a pointer for allowing the computerto recognize that the cursor has been positioned at the position of thetarget by the input operation of the test subject.

[0024] However, it is preferable that a touch panel comprising atransparent matrix switch is overlaid on the display screen so that thecorresponding target is pointed when the test subject presses theposition corresponding to the target on the touch panel overlaid on thescreen, in order to avoid large errors from occurring a result of theskill and delay for operating the cursor and pointer by the test object.

[0025] While the targets pressed by the test subject in a correct ordermay be left behind on the screen in the method according to the presentinvention, it is preferable that the targets pointed in a correct orderare erased from the screen in order to avoid misunderstanding of thepointing order and repeatedly pressing the same target.

[0026] However, the conditions for searching the targets turn out to beeasier at the later order of search when the number of the targetsdisplayed on the screen decreases by erasing the pointed targets.Consequently, the target may be so readily and promptly searched thatdelay due to fatigue is hardly detected.

[0027] Accordingly, dummy targets are displayed in place of the erasedtargets at random positions or at the position of the erased targets inthe present invention, when the targets are pointed in a correct order.It is therefore desirable that the targets are searched under the samecondition irrespective of the order of search, or under the conditionsthat the targets are searched in a correct order among the constantnumber of similar images displayed on the screen, in order to sharplyreflect the delay of the search response time due to fatigue.

[0028] The targets as used herein is not restricted to the target to beimmediately searched, but includes the targets to be searched andpointed sooner or later. The targets comprise images provided with marksrepresenting the order of pointing, for example figures, alphabets orJapanese letters (katakana or hiragana), or images comprising the marksthemselves indicating the order of pointing.

[0029] The dummy target comprises an image displayed by a similarconfiguration to each target, and is displayed at the position of theerased target, or at random positions. While the dummy target may havethe same color, shape and size as those of the target, at least one ofthe color, shape and size of the dummy target may be different fromthose of the target for simplifying search of the target to some extent.

[0030] When the mark indicating the order of pointing is displayed as atarget, or displayed in addition to the target, a mark other than themarks already displayed may be displayed as a dummy target, or may bedisplayed in addition to the dummy target, so that search operations aresimplified to some extent. At least one of the color, shape and size ofthe target may be different from those of the dummy target, or a dummytarget not attached with the mark may be displayed in place of theerased target and mark, when a mark indicating the order of pointing isdisplayed in addition to the target.

[0031] The display position for the target may be fixed in the presentinvention, or may be changed every time when the target has been pointedin a correct order. The display position for the dummy target may bealso fixed, or may be changed every time when the target has beenpointed in a correct order.

[0032] The search response time is contracted in descending order ofsearch, by the parallel processing of search of a target and memory ofthe other targets and dummy targets, or by operating the working memory,when the display position of the target and dummy target are fixed.

[0033] The search response time is further contracted in descendingorder of search, particularly when at least one of the color, shape andsize of the dummy target is different from those of the target for easyrecognition of the decreased number of the targets.

[0034] When the display positions of a target, or the display positionsof the target and a dummy target are changed every time when the targethas been pointed in a correct order, on the contrary, the memory of thetest subject is hardly reflected on contraction of the search responsetime since the memory on the target position before pointing the lasttarget is invalid. Consequently, the search response time is prolongedby fatigue as the search order is descending.

[0035] While visual disorder such as presbyopia, cataract and glaucomamay result in delay of the search response time in the method accordingto the present invention, the effect of such delay can be solved bydevising the size, shape and color of the target, and the backgroundcolor.

[0036] It was proved in the course of development of the presentinvention that highly reliable calculation results are obtained byexecuting the test 1, test 2 and test 3 in a prescribed order, measuringthe search response time required for searching the targets in each testfor every targets, and calculating the mentation age of the testsubject's brain based on the measured values. The contents of the test1, test 2 and test 3 are as follows:

[0037] The test 1 comprises the steps of displaying a given number oftargets to be pointed in a prescribed order by randomly distributingthem on the screen of a display device, allowing a test subject to pointeach target in a prescribed order, and displaying a dummy target havinga different color from the target at the position of the pointed targetin place of the pointed target when the target is pointed in a correctorder;

[0038] The test 2 comprises the steps of displaying a given number oftargets to be pointed in a prescribed order by randomly distributingthem on the screen of a display device, allowing a test subject to pointeach target in a prescribed order, and displaying a dummy target atrandom positions in place of the pointed target when the target ispointed in a correct order; and

[0039] The test 3 comprises the steps of displaying a given number oftargets to be pointed in a prescribed order by randomly distributingthem on the screen of a display device, allowing a test subject to pointeach target in a prescribed order, and displaying a dummy target atrandom positions in place of the pointed target when the target ispointed in a correct order, besides changing the display positions ofeach target and dummy target.

[0040] The number of the targets displayed is not particularlyrestricted, but 25 targets may be initially displayed as in theconventional TMT method.

[0041] It is preferable to disregard the search response timescorresponding to the targets from the first to a prescribed order, forexample from the first to the fifth targets, in each test from the testdata considering emotional tension and the effect of unaccustomed workat the beginning of the test.

[0042] With respect to the search response times for the targetsthereafter, the targets are divided into two groups of the first halftargets of sixth to 15^(th) and last half targets of 16^(th) to 25^(th)in order to simplify the mentation test, and the mentation test iscalculated based on the sum of the first half search response times andlast half search response times.

[0043] The mentation age of the test subject's brain is actuallycalculated based on the results of the first half of the test 1, thelast half of the test 2, the first half of the test 3 and the last halfof the test 3, because a strong correlation with the age has beenobserved among the first half of the test 1 as a sum of the searchresponse times from the sixth to the 15^(th) in the test 1, the lasthalf of the test 2 as a sum of the search response times from the16^(th) to the 25^(th) in the test 2, the first half of the test 3 as asum of the search response times from the sixth to the 15^(th) in thetest 3, and the last half of the test 3 as a sum of the search responsetimes from the 16^(th) to the 25^(th) in the test 3.

[0044] Equations (regression functions) are used for the stepwiseregression analysis with a regression curve correction, which arerepresented by the following equations 1 and 2.${{Equation}\quad 1}:\begin{matrix}{X = {{0.0154 \times \left( {{first}\quad {half}\quad {of}\quad {task}\quad A} \right)} + {0.00978 \times}}} \\{{\left( {{last}\quad {half}\quad {of}\quad {task}\quad C} \right) - {0.005535 \times}}} \\{{\left( {{first}\quad {half}\quad {of}\quad {task}\quad C} \right) + {0.003645 \times}}} \\{{\left( {{last}\quad {half}\quad {of}\quad {task}\quad B} \right) - 3.681}} \\{{\left( {{distinction}\quad {of}\quad {sex}} \right) - 6.612}}\end{matrix}$

[0045] The “distinction of sex” is substituted with 1 or 2 when the testsubject is male or female, respectively.

[0046] Equation 2:

ATMT calculated age (Y)−−0.0091X ²+1.8771X−19.192

[0047] While the mentation age of the test subjects' brain is somewhatdistributed in their twenties, it is close to the actual age in theirthirties or more, showing that this method is highly reliable.

[0048] The test subject may be informed of his (her) mentation state atthe test site in the method according to the present invention, when thesearch response time in each test is displayed on the screen immediatelyafter completing the entire tests. The test subject can enjoy thementation test of the brain as if he (or her) is playing a game, becausethe test subject is able to learn his (her) mentation age of the brainat the test site when the calculated mentation age of the test subject'sbrain is displayed on the screen after completing the entire tests.

[0049] It was also proved in the course of development of the methodaccording to the present invention that presence of dementia orprediction probability of onset of dementia can be decided from thecalculated values obtained by executing the test 2 and the test 3 in aprescribed order, measuring the search response time required forsearching each target in each test, and calculating the ratio of thesearch response time in the test 3 against the search response time inthe test 2.

[0050] It was proved that the ratio is 0.85 or more for the dementiapatients while the ratio is less than 0.85 for most of the normalsubjects, when the ratio of the search response time in the test 3against the search response time in the test 2 (the contraction ratio)is calculated.

[0051] Accordingly, presence of early stage dementia can be diagnosedwhether the ratio is 0.85 or more or not. When the ratio is less than0.85, it is possible to diagnose prediction probability of onset ofdementia by the calculation result or by the percentage obtained basedon the calculation result.

[0052] When the result of the diagnosis, or the ratio of the searchresponse time of the last half of the test 3 relative to the searchresponse time of the last half of the test 2, is 0.85 or less, the testsubject can be informed of the prediction probability of onset ofdementia at the test site by displaying the ratio or the percentagecalculated based on the ratio after completing the entire tests as theprediction probability of onset of dementia. When the search responsetime for each test is displayed on the screen after completing theentire tests, the test subject can also recognize his (her) mentationstate at the test site.

[0053] Of course, the test results of various mentations may be printedout with a printer, expressed as a voice output, or recorded on anappropriate recording medium.

[0054] A simple task in which the targets are pointed in a order of“1→2→3→ . . . ”, “A→B→C→ . . . ”, “a→b→C→ . . . ” and “α→β→γ→ . . . ”may be employed in the method according to the present invention.However, an optimum test tailored for the intelligence level of a testsubject may be also possible by permitting the test subject to select ahigher rank of task such as a combination of two or more sorts of orders(a category shift task) such as “1→a→2→b→c . . . ” or a inverse orderdistracter task such as “25→24→23→ . . . ” as in the TMT-B task.

[0055] Otherwise, emergence patterns and coordinates of the targets maybe previously determined in the test 3 while displaying dummy targetsevery time at random positions, which enables cerebral dominanthemisphere and visual field disorders such as constriction of peripheralattention visual field to be tested from the previously storedcoordinates of the targets (vectors) and their search response times.

[0056] The mentation test apparatus according to the present invention(referred as an apparatus according to the present inventionhereinafter) for attaining the foregoing objects employs a technicalmethod comprising: a display device for displaying images by electroniccontrol; a transparent touch panel overlaid on the screen of the displaydevice; an image control device for randomly displaying a given numberof targets to be pointed in a prescribed order on the screen byelectronic control of the display device, and for erasing the targetsthat have been pointed in a correct order when a test subject havepointed the targets by pressing the positions on the touch panelcorresponding to each target in a prescribed order; a time counter formeasuring the search response time required for the test subject tosearch the targets in a correct order and/or the search response timerequired for the test subject to search a given number of the targets ina continuous order; and a processing unit for calculating the testsubject's mentation based on the search response time measured with thetime counter.

[0057] In the method described above, a given number of the targets tobe pointed in a prescribed order are displayed on the screen by beingrandomly distributed, the search response time required for the testsubject to search each target is measured by allowing the test subjectto point each target in a prescribed order, and the mentation of thetest subject is calculated based on the measured values.

[0058] Detailed description of the method according to the presentinvention is omitted herein in order to avoid repeated explanations,since the display device has been described in the section of thedetailed description of the invention.

[0059] The touch panel comprises, as is now in the art; a matrix of anumber of switching elements using a transparent electrode. The displaypositions are transferred into the image control device as coordinateswhen the switching element corresponding to each target on the screen ispressed.

[0060] The image control device is provided with a function for allowinga given number of the targets to display on the screen of the displaydevice by randomly distributing them.

[0061] Actually, the image control device comprises, for example, a database that stores an initial display panel table in which the coordinatesof a given number of the targets displayed on the initially displayedscreen (initial screen) are recorded, and a main unit for controllingthe display device based on the read-out data from this data base andinput data from the touch panel.

[0062] Consequently, the main unit reads the disposition (emergencepattern) of the targets and dummy targets displayed on the screen fromthe data base, and controls the display device to display the targetsand dummy targets on the screen.

[0063] Although the display positions of the targets have beenpreviously determined as coordinates in this emergence pattern, thedisplay position of each target is actually determined so that eachtarget is displayed at random positions on the screen.

[0064] The image control device is also provided with a function forhalting display of the corresponding targets when the main unit reads acoordinate of a switching element pressed through the touch panel, andwhen the coordinate coincides with the coordinate of a correct target,and a function for erasing the corresponding target from the screen.

[0065] The image control device allows the display device to display thedummy target at the position of the erased target or at random positionsin place of the erased target, in order to maintain the condition thatthe targets are searched in a correct order among a given number ofresembling targets displayed on the screen.

[0066] The data with regard to the color, shape, size and displayposition of the dummy target may be stored, for example, in the database.

[0067] When the image control device permits the display device todisplay a mark indicating the order of pointing as a target, the displaydevice displays a mark other than the mark that has been alreadydisplayed at the position of the erased target or at random positions inplace of the erased target, in order to prevent misunderstanding of thepointing order or repeated pressing.

[0068] When the figures of 1 to 25 are displayed as the targets, forexample, the figure of “26” is displayed at the position where thefigure “1” has been displayed or at random positions as a dummy targetin place of the figure “1” when the figure “1” has been pointed anderased from the screen. Likewise, when the image control device allowsthe display device to display a mark indicating the order of pointing inaddition to the target, the display device displays a dummy targettogether with a mark other than the mark that has been already displayedat the position of the erased target or at random positions in place ofthe erased target, in order to prevent misunderstanding of the pointingorder or repeated pressing.

[0069] While an image comprising the same color, shape and size as thoseof the target may be used as the dummy target, the image control devicemay permit the display device to display a dummy target in which atleast one of the color, shape and size is different from those of theerased target, thereby enabling the range of the search area of theremaining targets to be narrowed and the search response time to becontracted.

[0070] The data base may be made to store the emergence pattern of thetargets before the targets are pointed and the emergence pattern of theremaining targets and dummy targets after each target has been pointed,besides making the display position of each target in each emergencepattern to be different to one another. As such, the image controldevice reads the emergence pattern of the remaining targets and dummytargets after the targets have been pointed every time when the targetshave been pointed in a correct order, or allows the display device todisplay each target that has not been pointed yet and dummy target bychanging their display positions.

[0071] When the image control device comprises a function for permittingthe display device to display each target at a fixed position until allthe targets have been sequentially pointed, a function for allowing thedisplay device to display the remaining targets by changing theirdisplay position every time when a target has been pointed, and aselection unit for making any one of the functions effective, both tasksof the tests in which the target positions are fixed and the targetpositions are changed may be simultaneously executed.

[0072] For example, the tests available comprise the test 1 in which agiven number of the targets to be pointed in a prescribed order aredisplayed on the screen of the display device by being randomlydistributed, the test subject is requested to point each target in aprescribed order, and a dummy target having a different color from thepointed target is displayed at the position of the pointed target inplace of the pointed target when the target has been pointed in acorrect order; or the test 2 in which a given number of the targets tobe pointed in a prescribed order are displayed on the screen of thedisplay device by being randomly distributed, the test subject isrequested to point each target in a prescribed order, and a dummy targetis displayed at the position of the pointed target in place of thepointed target when the target has been pointed in a correct order; andthe test 3 in which a given number of the targets to be pointed in aprescribed order are displayed on the screen of the display device bybeing randomly distributed, the test subject is requested to point eachtarget in a prescribed order, and a dummy target is displayed at theposition of the pointed target in place of the pointed target whilechanging the display positions of each target and dummy target when thetarget has been pointed in a correct order.

[0073] Three sorts of tests according to the functions below areavailable, when the method according to the present invention comprisesa function for displaying the targets by fixing their positions untilall the targets have been sequentially pointed, besides displaying adummy target having a different color from the pointed target in placeof the pointed target, a function for displaying the targets by fixingtheir positions until all the targets have been sequentially pointed,besides displaying a dummy target at random positions in place of thepointed target, a function for displaying the remaining targets bychanging their positions every time when a target has been pointed, anda selection unit for making any one of the functions effective.

[0074] For example, the tests available comprise the test 1 in which agiven number of the targets to be pointed in a prescribed order aredisplayed on the screen of the display device by being randomlydistributed, the test subject is made to point each target in aprescribed order, and a dummy target having a different color from thepointed target is displayed at the position of the pointed target inplace of the pointed target when the target has been pointed in acorrect order; the test 2 in which a given number of the targets to bepointed in a prescribed order are displayed on the screen of the displaydevice by being randomly distributed, the test subject is made to pointeach target in a prescribed order, and a dummy target is displayed atrandom positions in place of the pointed target when the target has beenpointed in a correct order; and the test 3 in which a given number ofthe targets to be pointed in a prescribed order are displayed on thescreen of the display device by being randomly distributed, the testsubject is made to point each target in a prescribed order, and a dummytarget is displayed at random positions in place of the pointed targetwhile changing the display positions of each target and dummy targetwhen the target has been pointed in a correct order.

[0075] It is of course possible to set various functions other thanthose described above such as a function for allowing the emergencepattern (display positions), color, shape, size and background color ofthe targets and dummy targets to change, by appropriately selecting thedata stored in the data base and control program in the image controldevice.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0076] The mentation test method and mentation test apparatus in anembodiment of the present invention will be described with reference tothe drawings.

[0077] As shown in the construction diagram in FIG. 1, the mentationtest apparatus in an embodiment according to the present inventioncomprises: a display device 1 for displaying an image by electroniccontrol; a transparent touch panel 2 overlaid on the screen of thedisplay device 1; an image control device 3 for randomly distributingand displaying a given number of targets to be pointed in a prescribedorder on the screen by controlling the display device 1, and for erasinga target pointed in a prescribed order by allowing a test subject pointthe target by pressing the position corresponding to the target on thetouch panel in a prescribed order; a time counter 4 for measuring thesearch response time required for the test subject to search the targetsin a correct order, and or the search response time required for thetest subject to search a given number of the targets having a sequentialorder; a processing unit 5 for calculating the test subject's mentationbased on the search response time measured with the time counter 4; andCPU 6 and ROM 7 for controlling these devices.

[0078] For example, a 17 inch CRT display device is used for the displaydevice 1. A number of switching elements comprising a transparentelectrode are aligned into a matrix in the touch panel 2 as known in theart, and the switch panel at the position corresponding to a target isturned on when the target displayed on the display device 1 is pressedfrom over the touch panel to input the coordinate of the displayposition of the target into the image control device 3.

[0079] The image control device 3 comprises a data base 31 storing aninitial screen table for recording the coordinates, colors, shapes andsizes of 25 targets to be displayed on the screen (the initial screen),a main unit 32 for controlling the display device 1 based on the dataread from the data base 31 or the data transferred from the touch panel2, and a selection unit 33 to be described hereinafter.

[0080] A screen table having different dispositions of the targets anddummy targets after the targets have been pointed, for example a tablefilled with the data of 24 sorts of emergence patterns, are stored inthe data base 31, in addition to the initial screen table. The colors,shapes and sizes of the dummy targets are also stored in the data base31.

[0081] The main unit 32 is waiting for the test subject to point thefirst target, after reading the initial screen table from the data base31 and randomly distributing and displaying 25 targets on the screen ofthe display device 1. As shown in the pattern diagram in FIG. 2, thebackground of the screen is colored to pale bluish gray, and each targetis displayed as a black circular button with an appropriate size inwhich a mark comprising a figure indicating the order of pointing isdisplayed as a white contrast in the gray background.

[0082] The main unit 32 allows the display position of the target to befixed and displayed until all the targets have been sequentiallypointed. Also, the main unit comprises a function for displaying a dummytarget having a different color from the pointed target in place of thepointed target, a function for fixing the display position anddisplaying the target until all the targets have been pointed, besidesdisplaying a dummy target at random positions in place of the pointedtarget, and a function for displaying the remaining targets by changingtheir positions every time when a target has been pointed. Any one ofthese functions is selected and effectively used by the selection unit33.

[0083] For example, suppose the coordinate of the first target isimputed from the touch panel 2 when the first function is selected withthe selection unit 33. Then, display of the target at the input positionis halted as shown in the pattern diagram in FIG. 3, and a dummy targetread from the data base is displayed at the corresponding position inplace of the target.

[0084] While the dummy target is displayed as a circular button with thesame shape and size as the target and with a figure indicating thepointing order displayed as a white contrast, the color of the dummytarget is changed to orange color.

[0085] Suppose the coordinate of the first target is imputed from thetouch panel 2 when the second function is selected with the selectionunit 33. Then, display of the target at the input position is halted asshown in the pattern diagram in FIG. 4, instead a dummy target read fromthe data base is displayed at the corresponding position of the erasedtarget.

[0086] The dummy target configured as a black circular button with thesame shape and size as those of the target, and a figure that has notbeen displayed, for example “26” when the first target is pointed or“27” when the second target is pointed, is displayed as a whitecontrast.

[0087] Suppose the coordinate of the first target is imputed from thetouch panel 2 when the third function is selected with the selectionunit 33. Then, display of the target at the input position is halted asshown in the pattern diagram in FIG. 5, and a dummy target read from thedata base is displayed in place of the target.

[0088] The display image table of the modified display positions of thetargets and dummy targets after, for example, the first target has beenpointed is read from the data base in this case, and the targets anddummy targets are randomly rearranged and displayed in accordance withthe data.

[0089] A figure that has not been displayed is displayed as a whitecontrast in this black circular dummy target with the same shape andsize as those of the target, as in the second function.

[0090] The order for selecting these functions is not particularlyrestricted, and the selection may be switched either manually orautomatically.

[0091] The mentation test method in an embodiment according to thepresent invention is carried out using, for example, the mentation testapparatus as described above.

[0092] The test is executed in the order of the test 1 in which a givennumber of the targets to be pointed in a prescribed order are displayedon the screen of the display device by being randomly distributed, thetest subject is made to point each target in a prescribed order, and adummy target having a different color from the pointed target isdisplayed at the position of the pointed target in place of the pointedtarget when the target has been pointed in a correct order; the test 2in which a given number of the targets to be pointed in a prescribedorder are displayed on the screen of the display device by beingrandomly distributed, the test subject is made to point each target in aprescribed order, and a dummy target is displayed at random positions inplace of the pointed target when the target has been pointed in acorrect order; and the test 3 in which a given number of the targets tobe pointed in a prescribed order are displayed on the screen of thedisplay device by being randomly distributed, the test subject is madeto point each target in a prescribed order, and a dummy target isdisplayed at random positions in place of the pointed target whilechanging the display positions of each target and dummy target when thetarget has been pointed in a correct order.

[0093] The time required for the test subject to search and point eachtarget in each test is measured with the time counter 4.

[0094] The measurements were carried out with respect to normal adultsof 40 males and 44 females with the age 18 or more and age 75 or less(mean age 43.2±17.0, S.D±1), respectively, as shown in Table 1. The meansearch response times for the test 1 (task A), test 2 (task B) and test3 (task C) were determined. TABLE 1 Age Distribution of Normal AdultsAGE MALE FEMALE TOTAL 18 to 19  1  4  5 20 to 29  9  8 17 30 to 39  6  915 40 to 49  9  5 14 50 to 59  6 10 16 60 to 69  8  5 13 70 to 79  1  3 4 TOTAL 40 44 84

[0095] For example, the mean search response time of 14 normal adults(nine males and five females) in their forties for each target was 2400to 2550 ms from the first through the fifth targets as shown in the twodimensional analysis of variance in FIG. 6, showing no evidentdifference among the tests. However, the mean search response time wasdelayed in the test 3 (task C) and contracted in the test 1 and test 2.

[0096] In the test 3 (task C), the dispositions of all the targets anddummy targets change every time when the targets have been pointed.Since the total number of the targets and dummy targets is unchanged,delay in the search response time seems to be caused by fatigue.

[0097] Since the positions of the target once appeared and of the dummytargets are unchanged in the test 2 (task B), search of a target andmemory of the display positions of the other targets and dummy targetsare processed in parallel. Accordingly, the score in the test 2 (task B)is contracted relative to the score in the test 3 (task C) due tooperation of the working memory.

[0098] A remarkable contraction is observed in the test 1 (task A) ascompared with the test 2 (task B). This is because the search area islimited to the targets that have not been pointed yet by changing thecolor of the dummy targets to the orange color that is different fromthe black color of the targets, besides the number of the targets thathas not been pointed is decreased, or the number of the buttons isdecreased.

[0099] After the similar tests carried out for each age range, thesearch response times for the first to fifth targets were omitted fromthe analysis considering the effects of tension and inexperience. Amongthe sixth to 25^(th) targets, the sixth to 15^(th) targets wereclassified as the first half targets and the 16^(th) to 25^(th) targetswere classified as the last half targets.

[0100] As shown in Table 2, the mean search response time was prolongedin all the tests as the ages of the test subjects are higher, showingdelay by aging. The results are more closely related to the age than theresults in the one-digit addition task (simplified task inUchida-Kraepelin's test) do, and a quite strong correlation with the agewere observed particularly in the last half of the test 2 (task B) andin the last half of the test 3 (task C). TABLE 1 SEARCH RESPONSE TIME(ms/target) PER ONE TARGET OBSERVED IN EACH AGE RANGE OF NORMAL ADULTS,AND RESULTS OF ONE-DIGIT ADDITION TASK ONE-DIGIT ADDITION TASK TASK ATASK B TASK C (CORRECT FIRST LAST FIRST LAST FIRST LAST ANSWERS/ AGE nHALF HALF HALF HALF HALF HALF 3 MIN) 18-19 5  1480 ±  975 ± 2118 ± 1755± 2391 ± 2619 ± 181.8 ±  345  251  458  295  432  600  26.1 20-29 17 1465 ±  864 ± 2076 ± 1810 ± 2189 ± 2672 ± 164.5 ±  272  169  391  195 290  349  20.5 30-39 15  1590 ±  924 ± 2282 ± 1990 ± 2389 ± 2900 ±163.0 ±  217  79  412  303  369  398  26.4 40-49 14  1769 ± 1045 ± 2467± 2215 ± 2669 ± 3254 ± 139.4 ±  237  173  345  346  317  497  19.6 50-5916  1989 ± 1321 ± 2671 ± 2383 ± 2782 ± 3683 ± 132.5 ±  294  239  368 390  322  441  28.1 60-69 13  2636 ± 1576 ± 3051 ± 3001 ± 3115 ± 3970 ±114.1 ±  377  331  364  617  400  617  31.2 70-74 4 35961 ± 2340 ± 3594± 3683 ± 4000 ± 4766 ± 101.8 ±  573  240  369  418  389  540  26.7CORRELATION 0.75*** 0.75*** 0.75*** 0.77*** 0.72*** 0.76*** 0.63*** WITHAGE

[0101] The search response time for each target in each test wassummarized in the fast half and last half of the test, respectively. Theratios (task A) between the fast half and last half (last half/firsthalf) in the test 1 (task A), and between the first half and last half(last half/first half) in the test 3 (task C), and the ratio of the lasthalf of the test 2 (task B) relative to the last half of the test 3(task C) were determined. As shown in Table 3, the search response timein the last half of the test was more contracted than that in the firsthalf of the test in any generation with respect to the ratio between thelast half and first half in the task A, showing no correlation with theage. TABLE 3 PARAMETERS ON THE TIME PERIOD REQUIRED FOR COMPLETING THETASK IN EACH GENERATION OF NORMAL ADULT RATIO OF LAST HALF OF TEST 3(TASK C) RELATIVE RATIO TO LAST BETWEEN HALF TEST RATIO FIRST HALF 2(TASK B) BETWEEN AND LAST LAST HALF FIRST HALF IN TEST OF TASK B/ HALFAND 3 (TASK C) LAST HALF LAST HALF LAST HALF/ OF TASK C IN TEST FIRSTHALF DEGREE OF 1 (TASK A) DEGREE CONTRACTION LAST HALF/ OF DELAY BYWORKING AGE n FIRST HALF BY FATIGUE MEMORY 18-19  5 0.66 ± 0.07 1.08 ±0.10 0.68 ± 0.08 20-29 17 0.60 ± 0.11 1.22 ± 0.08 0.69 ± 0.10 30-39 150.60 ± 0.11 1.25 ± 0.07 0.67 ± 0.07 40-49 14 0.60 ± 0.11 1.22 ± 0.070.68 ± 0.08 50-59 16 0.67 ± 0.13 1.33 ± 0.14 0.65 ± 0.08 60-69 13 0.60 ±0.08 1.27 ± 0.10 0.75 ± 0.07 70-74  4 0.66 ± 0.05 1.19 ± 0.14 0.77 ±0.06 CORRELATION n. s. 0.27* 0.24* WITH AGE

[0102] In the test 3 (task C), the search response time was more delayedin the last half than in the first half with a slight correlation withthe age, showing that the effect of fatigue was larger in the aged.

[0103] Since contraction of the search response time in the last half ofthe test 2 (task B) relative to the last half of the test 3 (task C) isconjectured to be caused by permitting the working memory to operate, acorrelation with the age that the working memory dulls in the higher agewas observed.

[0104] Since correlation of each search response time in the first halfand last half of the test 1 (task A), in the first half and last half ofthe test 2 (task B) and in the first half and last half of the test 3(task C) with aging was observed, the following equations 1 and 2 wereobtained from a step-wise regression analysis with additional correctionof curve. ${{Equation}\quad 1}:\begin{matrix}{X = {{0.0154 \times \left( {{first}\quad {half}\quad {of}\quad {task}\quad A} \right)} + {0.00978 \times}}} \\{{\left( {{last}\quad {half}\quad {of}\quad {task}\quad C} \right) - {0.005535 \times}}} \\{{\left( {{first}\quad {half}\quad {of}\quad {task}\quad C} \right) + {0.003645 \times}}} \\{{\left( {{last}\quad {half}\quad {of}\quad {task}\quad B} \right) - 3.681}} \\{{{\left( {{distinction}\quad {of}\quad {sex}} \right) - 6.612},}}\end{matrix}$

[0105] wherein the term “distinction of sex” is substituted with 1 or 2in male and female, respectively.

[0106] Equation 2:

ATMT calculated age (Y)=−0.0091X ²+1.8771X−19.192

[0107] As shown in the two dimensional dispersion analysis diagram withrespect to the correlation between the calculated age and actual age,the mentation age of the test subject's brain calculated as describedabove is highly reliable, since the calculated age is closelyapproximated with the actual age in the age thirties or more, although aslight distribution is observed in the age twenties.

[0108] Similarly, the test 1, test 2 and test 3 were applied to 17normal adults with the age sixty or more (nine males and eight females,mean age 66.9±4.6), and to 14 patients with mild senile dementia andboundary senile dementia (eight males and six females, mean age68.6±3.3) who visited the senile internal medicine clinic.

[0109] The patients with mild senile dementia and boundary seniledementia (referred as early dementia patients hereinafter) wererestricted to those who have experienced at least two times of episodesskeptical of symptoms of dementia and showing a Hasegawa's dementiascale of 22 or more and 27 or less.

[0110] The test subjects were divided into two groups of the normaladults and early dementia patients, and the mean search response timesin the first half and last half of each test in each group weredetermined by the same method as described above. The results are shownin Table 4. TABLE 4 COMPARISON OF NORMAL ADULTS AND DEMENTIA PATIENTS ATAGE 60 OR MORE ONE DIGIT ADDITION TASK TASK A TASK B TASK C (CORRECTFIRST LAST FIRST LAST FIRST LAST ANSWERS/3 n HALF HALF HALF HALF HALFHALF MIN) NORMAL 17 2853 ± 575 1756 ± 452 3178 ± 362 3161 ± 638  3323 ±545 4157 ± 745 111.2 ± 28.9 DEMENTIA 14 3697 ± 522 1949 ± 524 3891 ± 3694788 ± 1103 3963 ± 571 4923 ± 872  69.7 ± 16.4 SIGNIFICANT p < 0.001 p <0.001 p < 0.01 p < 0.001 p < 0.01 p <0.01 p < 0.001 DIFFERENGE BETWEENTWO GROUPS

[0111] The test subjects were also divided into two groups of the normaladults and early dementia patients, and the ratios between the firsthalf and last half (last half/first half) in the test 1 (task A), andbetween the first half and last half (last half/first half) in the test3 (task C), and the ratio of the last half of the test 2 (task B)relative to the last half of the test 3 (task C) were determined. Theresults are shown in Table 5. TABLE 5 COMPARISON OF PARAMETERS ON THETIME PERIOD REQUIRED FOR COMPLETING THE TASK IN NORMAL ADULTS ANDDEMENTIA PATIENTS AT AGE 60 OR MORE RATIO OF LAST HALF OF TEST RATIO BRELATIVE BETWEEN TO LAST HALF FIRST OF TEST C RATIO HALF AND LAST HALFBETWEEN LAST HALF OF TASK B/ FIRST IN TASK C LAST HALF HALF AND LASTHALF/ OF TASK C LAST HALF FIRST HALF DEGREE OF IN TASK A DEGREECONTRACTION LAST HALF/ OF DELAY BY WORKING n FIRST HALF BY FATIGUEMEMORY NORMAL 17 0.61 ± 0.08 125 ± 0.11 0.76 ± 0.07 DEMENTIA 14 0.79 ±0.08 124 ± 0.11 0.96 ± 0.93 SIGNIFICANT    p < 0.001 n. s.    p < 0.001DIFFERENCE BETWEEN TWO GROUPS

[0112] Table 5 shows that, while significant differences were observedbetween the normal adults and dementia patients in the ratio between thefirst half and last half (last half/first half) of the test 1 (task A),no difference was observed in the ratio between the first half and lasthalf (last half/first half) of the test 3 (task C) that is thought toindicate the degree of delay by fatigue.

[0113] The ratio of the last half of the test 2 (task B) relative to thelast half of the test 3 (task C) is conjectured to indicate the extentof application of the working memory, and a significant difference wasobserved between the-normal adults and early dementia patients.

[0114] To verify the difference between the normal adults and earlydementia patients, the ratios (the degree of contraction) of the lasthalf of the test 2 (task B) relative to the last half of the test 3(task C) for the 84 normal adults with their age in the range of 18 to74, and those of the early dementia patients were filled in the twodimensional dispersion analysis diagram shown in FIG. 8. It was revealedthat the values of the early dementia patients were completelydistributed in the range of 0.85 or more, in contrast to thedistribution of the normal adults of less than 0.85 with few exceptionsof three subjects in total of 84 subjects.

[0115] According to the mentation test method, the early dementiapatients can be detected with a detection ratio of 100% including 0% ofpseudo-negative ratio and 3.5% of pseudo-positive ratio, by calculatingthe ratio of the last half of the test 2 (task B) relative to the lasthalf of the test 3 (task C) and deciding whether the ratio is 0.85 ormore or less than 0.85.

[0116] The search response time is measured for each target, and thedisplay position of the target is stored as a coordinate in the database. Consequently, testing of dominance of the cerebral hemisphere andvisual field disorders such as constriction of peripheral attentionvisual field is possible based on the positional coordinates (vector) ofthe pointed targets and search response time in the test 3 (task C) inwhich the positional coordinates are changed every time when the targetshave been pointed.

[0117] The test method can be also applied for testing the degree ofmental function due to drinking and medication, or for testing thedegree of drinking, medication dose and side effect of medicines.

[0118] With respect to the effect of intake of alcohol on the testresults, a significant decrease of the test score can be detected in thetest subject who has exhibited no effect of alcohol on his sense ofequilibrium and behavior. A significant improvement of the testachievement after intake of caffeine can be also detected, showing theability of the test for quite sensitively detecting the mentation of thebrain.

[0119] The test subject can enjoy the mentation test of the brain as ifhe (or her) is playing a game, because the test subject is able to learnhis (her) mentation age of the brain at the test site when thecalculated mentation age of the test subject's brain is displayed on thescreen of the display device 1 after completing the entire tests.

[0120] When the apparatus according to the present invention isinstalled, for example, in the waiting room of a hospital, visitors ofthe hospital would be interested in finding early onset of dementia orin the probability of onset of dementia to make them easy to voluntarilyreceive the mentation test. This will enable onset of dementia to befound in its early stage, or probability of onset of dementia to beinformed, thereby giving an opportunity to be alert on onset ofdementia, or to take preventive measures against onset of dementia.

[0121] In the method according to the present invention, a given numberof the targets to be pointed in a prescribed order is randomlydistributed and displayed on the screen of the display device, thesearch response time required for the test subject to search each targetis measured by requesting the test subject to point each target in aprescribed order, and the mentation of the test subject is calculatedbased on the measured values. Accordingly, the mentation age of thebrain can be conjectured, and onset of early dementia and theprobability of onset of dementia can be diagnosed, besides enabling thedegree of drinking, the effects of medication and side effects ofmedication, the effects of rehabilitation of cerebrovascular disorder,dominance of cerebral hemisphere and peripheral attention visual fieldto be sensitively discriminated.

[0122] A highly reliable mentation test is possible without anycorrelation with educational carrier as seen in the Uchida-Kraepelin'sdementia scale, or without being affected by the effects of repeatedlearning as seen in the Hasegawa's dementia scale.

[0123] It is possible to repeatedly apply the mentation test within ashort period of time because no effects of the repeated learning areobserved, enabling the test to be quite favorably applied for the actionof medicines and side effects of medicines, decision of the effects ofrehabilitation of cerebrovascular disorder, and decision of the effectsof medicines.

[0124] Further, the test is promptly carried out by electronic controlto rapidly display the calculated results, for example the test resultsare displayed on the screen in place of the targets that have beendisplayed. Accordingly, the test subject can enjoy the test as if he (orshe) is playing a game, visitors of the hospital would be interested infinding early onset of dementia or in the probability of onset ofdementia to make them easy to voluntarily receive the mentation test byinstalling the apparatus in, for example, the waiting room of ahospital.

[0125] The apparatus according to the present invention comprises adisplay device for displaying the image by electronic control, atransparent touch panel overlaid on the screen of the display device, animage control device for randomly distributing and displaying a givennumber of the targets to be pointed in a prescribed order by controllingthe display device, and for erasing the targets that have been pointedin a correct order when the test subject presses the positioncorresponding to each target on thc touch panel in a prescribed order topoint the target, a time counter for measuring the search response timerequired for the test subject to search the target in a correct order,and/or the search response time required for the test subject to searcha given number of the continuous targets, and a processing device forcalculating the mentation of the test subject based on the searchresponse time measured by the time counter. Consequently, it is possibleto apply the method according to the present invention by which a givennumber of the targets to be pointed in a prescribed order are randomlydistributed and displayed on the screen of the display device, thesearch response time required for the test subject to search each targetis measured by allowing the test subject to point each target in aprescribed order and mentation of the test subject is calculated basedon the measured values.

[0126] The mentation age of the brain can be conjectured, and presenceof early onset dementia and prediction probability of onset of dementiacan be accurately diagnosed, besides enabling the degree of drinking,the effects of medicines and side effect of medicines, andrehabilitation effects of cerebrovascular disorder to be sensitively andaccurately decided with repetition within a short period of time.

[0127] When the apparatus according to the present invention isinstalled, for example, in the waiting room of a hospital, visitors ofthe hospital would be interested in finding early onset of dementia orin the probability of onset of dementia to make them easy to voluntarilyreceive the mentation test.

BRIEF DESCRIPTION OF THE DRAWINGS

[0128]FIG. 1 shows a construction diagram of the apparatus according tothe present invention.

[0129]FIG. 2 shows an emergency pattern of the targets on the initialscreen according to the present invention.

[0130]FIG. 3 shows an emergency pattern of the targets in test 1according to the present invention.

[0131]FIG. 4 shows an emergency pattern of the targets in test 2according to the present invention.

[0132]FIG. 5 shows an emergency pattern of the targets in test 3according to the present invention.

[0133]FIG. 6 shows a two dimensional dispersion analysis diagram of themean search response time of each target according to the presentinvention.

[0134]FIG. 7 shows a two dimensional dispersion analysis diagram of thecalculated age and actual age according to the present invention.

[0135]FIG. 8 shows a two dimensional dispersion analysis diagram of thedegree of contraction and age according to the present invention.

[0136] [Reference Numerals]

[0137]1: display device

[0138]2: touch panel

[0139]3: image control device

[0140]4: time counter

[0141]5: processing device

I claim:
 1. A mentation test method comprising: displaying randomlydistributed given number of targets to be sequentially pointed accordingto a prescribed order on a screen of a display means; measuring thesearch response time required for a test subject to search each targetby requesting the subject to sequentially point the targets according toa prescribed order; and calculating mentation of the test subject basedon the measured values.
 2. The mentation test method according to claim1, wherein the given number of the targets are displayed on a screen ofan electronic control display means, and the test subject points thetargets by pressing the locations corresponding to the targets on atouch panel overlaid on the screen.
 3. The mentation test methodaccording to claim 1 or 2, wherein the targets are erased from thescreen when they are pointed in a correct order.
 4. The mentation testmethod according to claim 3, wherein dummy targets are displayed inplace of the erased targets at the positions where the erased targetshave been located or at random positions when the targets are pointed ina correct order.
 5. The mentation test method according to claim 4,wherein at least one of the color, shape and size of the target aredifferent from those of the dummy target.
 6. The mentation test methodaccording to claim 4 or 5, wherein marks indicating the order ofpointing are displayed as the targets or in addition to the targets, andmarks other than those that have been already displayed are displayed asthe dummy targets or in addition to the dummy targets.
 7. The mentationtest method according to any one of claims 1 to 6, wherein displaypositions of the remaining targets that have not been pointed yet changeevery time when the other targets have been pointed in a correct order.8. The mentation test method according to claim 1 for executing, in aprescribed order, a test 1 in which a given number of the targets to bepointed in a prescribed order are displayed on the screen of the displaymeans by being randomly distributed, the test subject is requested topoint each target in a prescribed order, and a dummy target having adifferent color from the target is displayed in place of the pointedtarget at the position of the pointed target when the target is pointedin a correct order; a test 2 in which a given number of the targets tobe pointed in a prescribed order are displayed on the screen by beingrandomly distributed, the test subject is requested to point each targetin a prescribed order, and a dummy target is displayed in place of thepointed target at a randomly selected position when the target has beenpointed in a correct order; and a test 3 in which a given number of thetargets to be pointed in a prescribed order are displayed on the screenby being randomly distributed, the test subject is requested to pointeach target in a prescribed order, and a dummy target is displayed inplace of the pointed target at a randomly selected position when thetarget has been pointed in a correct order, besides changing the displaypositions of each target and dummy target, wherein the search responsetime required for searching the target in each test is measured forevery targets, and mentation age of the test subject's brain iscalculated based on the measured values.
 9. The mentation test methodaccording to claim 8 comprising the steps of: initially displaying 25targets in each test; disregarding the measured values for the first tofifth targets; and calculating the mentation age of the test subject'sbrain according to the equations 1 and 2 below based on the first halfof the test 1 in which the search times for the 6^(th) to 15^(th) pointsare summarized, the last half of the test 2 in which the search timesfor the 16 to 25 points are summarized, and the first half of the test 3in which the search times for the 6^(th) to 15^(th) points aresummarized, and the last half of test 3 in which the search times forthe 16^(th) to 25^(th) points are summarized:$\underset{\_}{{Equation}\quad 1}$ $\begin{matrix}{X = {{0.0154 \times \left( {{first}\quad {half}\quad {of}\quad {task}\quad A} \right)} + {0.00978 \times}}} \\{{\left( {{last}\quad {half}\quad {of}\quad {task}\quad C} \right) - {0.005535 \times}}} \\{{\left( {{first}\quad {half}\quad {of}\quad {task}\quad C} \right) + {0.003645 \times}}} \\{{\left( {{last}\quad {half}\quad {of}\quad {task}\quad B} \right) - 3.681}} \\{{\left( {{distinction}\quad {of}\quad {sex}} \right) - 6.612}}\end{matrix}$

wherein the term “distinction of sex” is substituted with 1 when thetest subject is a male, and 2 when the test subject is a female, andEquation 2 ATMT calculated age=−0.0091X ²+1.8771X−19.192
 10. Thementation test method according to claim 8 or 9, wherein the searchresponse time for each test is displayed on the screen after completingthe entire tests.
 11. The mentation test method according to any one ofclaims 8 to 10, wherein the calculated mentation age of the testsubject's brain is displayed on the screen after completing the entiretests.
 12. The mentation test method according to claim 1 for executing,in a prescribed order, the test 2 in which a given number of the targetsto be pointed in a prescribed order are displayed on the screen by beingrandomly distributed, the test subject is requested to point each targetin a prescribed order, and a dummy target is displayed in place of thepointed target at a randomly selected position when the target has beenpointed in a correct order; and the test 3 in which a given number ofthe targets to be pointed in a prescribed order are displayed on thescreen by being randomly distributed, the test subject is requested topoint each target in a prescribed order, and a dummy target is displayedin place of the pointed target at a randomly selected position when thetarget has been pointed in a correct order, while changing the displaypositions of each target and dummy target, wherein the search responsetime required for searching the target in each test is measured forevery targets, the ratio of the search response time in test 2 relativeto the search response time in test 3 is calculated, and presence ofdementia or prediction probability of onset of dementia is judged fromthe calculation results.
 13. The mentation test method according toclaim 12 comprising the steps of: initially displaying 25 targets ineach test; disregarding the measured values for the first to fifthtargets; and diagnosing a patient as a normal or a dementia patientbased on whether the ratio of the search response time in the last halfof the test 2 relative to the search response time in the last half ofthe test 3 is 0.85 or less, wherein the order of the 6^(th) to 15^(th)targets is defined as a first half of the test and the order of the16^(th) to 25^(th) targets is defined as a last half of the test. 14.The mentation test method according to claim 12 or 13 wherein, when theratio of the search response time in the last half of test 2 relative tothe search response time in the last half of test 3 is 0.85 or less, theratio or the percentage calculated based on the ratio is displayed onthe screen as a prediction probability of onset of dementia aftercompleting the entire tests.
 15. The mentation test method according toany one of claims 12 to 14, wherein the search response time in eachtest is displayed on the screen after completing the entire tests.
 16. Amentation test apparatus comprising: a display means for displayingimages by electronic control; a transparent touch panel overlaid on thescreen of the display means; an image control means for randomlydisposing and displaying a given number of targets to be pointed in aprescribed order on the screen by controlling the display means, and forerasing the targets that have been pointed in a correct order when atest subject points the target by pressing the position corresponding toeach target on the touch panel in a prescribed order; a time counter formeasuring the search response time required for the test subject forsearching the targets in a correct order, and/or the search responsetime required for the test subject for searching a given number oftargets arranged in a sequential order, and a processing means forcalculating the mentation of the test subject based on the searchresponse time measured by the time counter.
 17. The mentation testapparatus according to claim 16, wherein the image control meanscomprises a function for allowing the display means to display the dummytargets at the positions where the targets have been erased or at randompositions in place of the targets that have been erased.
 18. Thementation test apparatus according to claim 17, wherein the imagecontrol means comprises a function for allowing the display means todisplay the dummy targets being different in at least one of the color,shape and size in place of the targets that have been erased.
 19. Thementation test apparatus according to any one of claims 16 to 18,wherein the image control means comprises a function for allowing thedisplay means to display the marks indicating the order of pointing asthe targets or in addition to the targets, and for allowing the displaymeans to display the marks other than the marks that have been alreadydisplayed as dummy targets in place of the erased targets at thepositions of the targets that have been erased or at random positions,or in addition to the positions of the targets that have been erased orin addition to the randomly displayed dummy targets.
 20. The mentationtest apparatus according to any one of claims 16 to 19, wherein theimage control means comprise a function for allowing the display meansto display each target that has not been pointed yet by changing itsdisplay position every time when the other targets have been pointed ina correct order.
 21. The mentation test apparatus according to claim 16comprising a function for allowing the display means to erase a targetfrom the screen when the target is pointed in a correct order, and todisplay a dummy target having a different color at the position of thetarget in place of the target that has been erased; a function forallowing the display means to erase a target from the screen when'thetarget is pointed in a correct order, and to display a dummy target atrandom positions in place of the target that has been erased; a functionfor allowing the display means to erase a target from the screen whenthe target has been pointed in a correct order, and to display a dummytarget at random positions in place of the target that has been erased,while allowing the display means to display each target and dummy targetby changing their display positions; and a selection means for makingany one of the functions effective, wherein the mentation age of thetest subject's brain is calculated by the processing means based on thesearch response time measured by the time counter in the test using eachfunction.
 22. The mentation test apparatus according to claim 21,wherein the image control means allows the display means to display thesearch response time of each target measured by the time counter in eachtest after completing the entire tests.
 23. The mentation test apparatusaccording to claim 21 or 22, wherein the image control means allows thedisplay means to display the mentation age of the test subject's braincalculated by the processing means after completing the entire tests.24. The mentation test method according to claim 16 comprising: an imagecontrol means for executing, in a prescribed order, the test 2 byallowing the display means to erasing a target from the screen when thetarget is pointed in a correct order, and to display a dummy target onthe screen at random positions in place of the target that has beenerased, and the test 3 by allowing the display means to erase a targetfrom the screen when the target is pointed in a correct order, and todisplay a dummy target at random positions on the screen in place of thetarget that has been erased, while allowing the display means to displayeach target and dummy target by changing their display positions; aprocessing means for calculating the degree of contraction of the searchresponse time by a working memory for parallel processing of search andmemory of positions based on the search response time of each targetmeasured by the time counter in each test; and a diagnosis means fordiagnosing presence of dementia or prediction probability of onset ofdementia based on the calculation results.
 25. The mentation testapparatus according to claim 24, wherein the image control means allowsthe display means to display the search response time for each target ineach test measured by the time counter after completing the entiretests.
 26. The mentation test apparatus according to claim 24 or 25,wherein the image control means allows the display means to display theresults of diagnosis by the diagnosis means after completing the entiretests.
 27. The mentation test apparatus according to any one of claims16 to 26 comprising a printer for printing the test results.